The live rock thing I have not tried yet. I have been using a wet/dry for over 10 years in my fish only aggressive tanks. If it isnt broken, dont try to fix it. For years and years and years people used UNDERGRAVEL filters with success. Now, I wouldnt use one of those, but I can't complain about my wet/dry. By the way, I have NEVER touched the bio balls, NEVER EVER.....
I think as long as you maintain the quality of the water and have the correct mix of fish, the TYPE of filtration you use is not that vital, as long as it can support the ecosystem.....
(my very UN-professional advice)